It is known in the art to provide a linear synchronous magnetic motor as an electrodynamic brake. Such electrodynamic brakes are activated when the modules of the brake having permanent magnets of alternating polarity face one another, wherein each permanent magnet in each array faces and opposes a magnet of opposite polarity. The brakes can be deactivated by displacing one of the modules forward or backward 180 electrical degrees, which causes the magnetic field to diminish to a negligible level.
At present, such brakes are configured to be either fully in phase or out of phase, i.e., shifting the brakes 180 electrical degrees by fully displacing the module forward or backward or by lowering or raising a module away from the braking zone. It is also known to have such brakes configured to shift from one phase angle to another phase angle, e.g., from 180 electrical degrees to 90 electrical degrees, in order to provide an intermediate level of braking force. But no known system provides for the precise shifting of the modules to selected phase angles to provide the application of a number of selected braking forces.
Thus, there exists a need for an apparatus and method that provides for the incremental and precise application of braking force of an eddy current brake. For example, a brake configured to be shifted to any selected phase angle, rather than simply from one phase angle to another phase angle, would be most desirable. And there exists a need to do so with accurate metering, the type of which could not be achieved by a system that employed only double-acting piston cylinders.
It would be further desirable to link such a brake to a control system whereby a selected phase angle, which in turn translates to a selected braking force, could be selected on the basis of a selected condition such as velocity of the incoming vehicle and environmental factors. A system that determines the incoming velocity, for example, an object and applies a precise braking force based on that reading would be desirable. Such a system would allow for precise braking to occur in the event that the object or vehicle approaching the braking zone is not traveling at the designed or intended velocity due to external or unforeseen influences such as temperature, fluctuations in mass, or variable drag coefficients that are imposed on the moving vehicle. In most instances, achieving the desired incremental application of brake force is not possible due to the high difficulty of displacing the opposing modules forward and slightly downward brought on by mechanical interference that occurs surrounding the motor module, and due to the magnetic force between the modules which tends to push the opposing magnets in the module toward equilibrium.